fight-or-flight reaction

fight-or-flight reaction

n.

A set of physiological changes, such as increases in heart rate, arterial blood pressure, and blood glucose, initiated by the sympathetic nervous system to mobilize body systems in response to stress. Also called emergency theory.

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fight-or-flight reaction

coordinated result of increased secretion of adrenal medullary hormones and of stimulation and resulting increased activity of the sympathetic nervous system. Creates the optimum situation for the survival of the individual by fighting the adversary or fleeing from it. The reaction comprises constriction of the blood vessels of alimentary tract and skin but dilatation of those to skeletal muscles; increased cardiac rate and output, and coronary dilatation occur; also elevation of the blood sugar levels and metabolic rate, dilatation of the pupils, evacuation of blood from the spleen, bronchodilatation, piloerection and decrease in coagulation time.